Light emitting diode structure

ABSTRACT

A light emitting diode includes a base layer, an electric contact layer, a semiconductor stack, and an insulation layer. The base layer has a maximum of a first width. The electric contact layer has a maximum of a second width and is disposed on the base layer. The semiconductor stack disposed on the electric contact layer has a maximum of a third width, and includes a first type semiconductor layer, a light emitting layer, and a second type semiconductor layer stacked in sequence, wherein a width of the first type semiconductor layer is smaller than the maximum of the third width. The insulation layer covers the sidewalls of the base layer, the electric contact layer, and the semiconductor stack. The maximum of the second width is greater than the maximum of the third width and the maximum of the second width is less than the maximum of the first width.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Serial Number107129676, filed Aug. 24, 2018, which is herein incorporated byreference.

BACKGROUND Field of Invention

The present invention relates to a light emitting diode structure.

Description of Related Art

As comparing to the conventional light emitting diode, the size of themicro light emitting diode (micro LED) is reduced to a level of micronmeters (pm), and the target yield of manufacturing the micro LEDs isaimed to be over 99%. However, conventional processes of fabricatingmicro LEDs face various technical challenges, in which the mass transfertechnology is the most crucial process. Furthermore, many othertechnical problems need to be resolved, for example the precision of theequipment, the transfer yields, the transfer time, the rework property,and the processing cost.

For example, the current technology for manufacturing a micro lightemitting diode is to first define a micro light emitting diode structureby processes, and then the micro light emitting diode structure isbonded to a first temporary substrate and the sapphire substrate isremoved by laser lift-off (LLO) technology. The micro light emittingdiode structure is then bonded to a second temporary substrate by usinga bonding material. Next, after removing the first temporary substrateand manufacturing a supporter structure, the bonding material is etched,and the epitaxial structure in the micro light emitting diode structureis finally transferred. In the processes above, it requires two times ofbonding the temporary substrate and two times of removing the temporarysubstrate. In addition to the poor control of the yield loss, after thestress of the epitaxial structure is released, the spacing pitch betweenthe micro light emitting diodes is also different from the originaldesign, thereby causing the alignment problem during the transfer.

SUMMARY

One aspect of the present invention provides a light emitting diodestructure. The light emitting diode structure includes a base layer, anelectric contact layer, a semiconductor stack, and an insulation layer.The base layer has a maximum of a first width. The electric contactlayer has a maximum of a second width and is disposed on the base layer.The semiconductor stack has a maximum of a third width and is disposedon the electric contact layer. The semiconductor stack includes a firsttype semiconductor layer, a light emitting layer, and a second typesemiconductor layer stacked in sequence, wherein a width of the firsttype semiconductor layer, a width of the light emitting layer, and awidth of the second type semiconductor layer are substantially smallerthan or equal to the maximum of the third width. The insulation layercovers at least a sidewall of the base layer, a sidewall of the electriccontact layer, and a sidewall of the semiconductor stack. The maximum ofthe second width is greater than the maximum of the third width and themaximum of the second width is less than or equal to the maximum of thefirst width.

According to some embodiments of the present disclosure, the electriccontact layer is a single layer. The maximum of the second width issubstantially equal to the maximum of the first width.

According to some embodiments of the present disclosure, the electriccontact layer includes an ohmic contact layer and a first metal layer.The ohmic contact layer with a maximum of a fourth width is disposedbetween the semiconductor stack and the base layer and the first metallayer with a maximum of a fifth width is disposed between the ohmiccontact layer and the base layer. The maximum of the fourth width issmaller than or substantially equal to the maximum of the first widthand the maximum of the fifth width is substantially equal to the maximumof the first width.

According to some embodiments of the present disclosure, the maximum ofthe fourth width is substantially equal to the maximum of the thirdwidth.

According to some embodiments of the present disclosure, the lightemitting diode structure further includes an electrode layer disposed onthe semiconductor stack.

According to some embodiments of the present disclosure, the electrodelayer is transparent for a light emitted from the light emitting layer.

According to some embodiments of the present disclosure, the electrodelayer is a second metal layer.

According to some embodiments of the present disclosure, the base layerincludes a dielectric material or a metal material.

According to some embodiments of the present disclosure, the base layerincludes a distributed bragg reflector and the insulation layer coversat least a sidewall of the distributed bragg reflector.

According to some embodiments of the present disclosure, the electriccontact layer is transparent for a light emitted by the light emittinglayer.

Another aspect of the present invention provides a light emitting diodestructure. The light emitting diode structure includes a semiconductorstack, an insulation layer, a first conductive pad, a second conductivepad, and a supporting breakpoint. The semiconductor stack includes afirst type semiconductor layer, a light emitting layer, and a secondtype semiconductor layer stacked from top to bottom in sequence, whereinthe second type semiconductor layer comprises a first portion and asecond portion and the first portion is disposed on the second portion.A maximum width of the second portion is greater than a maximum width ofthe first portion. The insulation layer covers a sidewall of thesemiconductor stack and an upper surface of the second portion. Theinsulation layer has a first opening and a second opening respectivelylocated on the first type semiconductor layer and the second portion.The first conductive pad is electrically connected to the first typesemiconductor layer through the first opening. The second conductive padis electrically connected to the second portion through the secondopening. The supporting breakpoint is disposed over the insulation layerand between the first conductive pad and the second conductive pad.

According to some embodiments of the present disclosure, the lightemitting diode structure further includes a bonding substrateelectrically connected to the first conductive pad and the secondconductive pad.

According to some embodiments of the present disclosure, the lightemitting diode structure further includes a first adhesive layer and asecond adhesive layer. The first adhesive layer is disposed between thefirst conductive pad and the bonding substrate, the second adhesivelayer is disposed between the second conductive pad and the bondingsubstrate, and the first adhesive layer is electrically insulated fromthe second adhesive layer.

According to some embodiments of the present disclosure, the lightemitting diode structure further includes an electrode layer disposedbetween the first type semiconductor layer and the first conductive pad.

According to some embodiments of the present disclosure, the lightemitting diode structure further includes a conductive block disposed inthe second opening, in which the second conductive pad covers a sidewalland a top surface of the conductive block.

According to some embodiments of the present disclosure, a top surfaceof the insulation layer positioned on the first portion of the secondtype semiconductor layer is substantially level with the top surface ofthe conductive block.

According to some embodiments of the present disclosure, the firstconductive pad extends to cover a portion of the insulation layer.

According to some embodiments of the present disclosure, a top surfaceof the first conductive pad is substantially level with a top surface ofthe second conductive pad.

According to some embodiments of the present disclosure, the second typesemiconductor layer has a surface exposed outside and the surface has arough texture.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1A and 1B are cross-sectional views of the light emitting diodestructure, in accordance with various embodiments of the presentinvention.

FIG. 2 is cross-sectional view of the light emitting diode structure, inaccordance with another embodiment of the present invention.

FIG. 3 is cross-sectional view of the light emitting diode structure, inaccordance with yet another embodiment of the present invention.

FIG. 4 to FIG. 11B are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure, inaccordance with one embodiment of the present invention.

FIG. 12 is top view illustrating one process stage of manufacturing thelight emitting diode structure, in accordance with one embodiment of thepresent invention.

FIG. 13 to FIG. 15 are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure, inaccordance with the line A-A′ in FIG. 12.

FIG. 16A to FIG. 16B are cross-sectional views illustrating one processstage of manufacturing the light emitting diode structure, in accordancewith the line B-B′ in FIG. 12.

FIG. 17 to FIG. 25 are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure, inaccordance with another embodiment of the present invention.

FIG. 26 to FIG. 34 are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure, inaccordance with another embodiment of the present invention.

FIG. 35 is top view illustrating one process stage of manufacturing thelight emitting diode structure, in accordance with another embodiment ofthe present invention.

FIG. 36 to FIG. 38A are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure,along line A-A′ in FIG. 35.

FIG. 38B is cross-sectional view illustrating one process stage ofmanufacturing the light emitting diode structure, along the line B-B′ inFIG. 35.

FIG. 39 to FIG. 50 are cross-sectional views illustrating variousprocess stages of manufacturing the light emitting diode structure, inaccordance with yet another embodiment of the present invention.

DETAILED DESCRIPTION

The present disclosure is described by the following specificembodiments. Those with ordinary skill in the arts can readilyunderstand the other advantages and functions of the present inventionafter reading the disclosure of this specification. The presentdisclosure can also be implemented with different embodiments. Variousdetails described in this specification can be modified based ondifferent viewpoints and applications without departing from the scopeof the present disclosure.

The following embodiments are disclosed with accompanying diagrams fordetailed description. For illustration clarity, many details of practiceare explained in the following descriptions. However, it should beunderstood that these details of practice do not intend to limit thepresent invention. That is, these details of practice are not necessaryin parts of embodiments of the present invention. Furthermore, forsimplifying the drawings, some of the conventional structures andelements are shown with schematic illustrations.

FIG. 1A and 1B are cross-sectional views schematically illustrating alight emitting diode structure 10, in accordance with variousembodiments of the present invention. Referring to FIG. 1A and FIG. 1B,the light emitting diode structure 10 disclosed herein includes a baselayer 110, an electric contact layer 120, a semiconductor stack 130, andan insulation layer 140.

As shown in FIG. 1A and FIG. 1B, in particular, the base layer 110 has amaximum of a first width W1. More specifically, the base layer 110 mayhave a trapezoidal profile in a cross-sectional view in practicalimplementation. In various embodiments, the base layer 110 may include adielectric material or a metal material. For example, the examples ofdielectric material include silicon dioxide (SiO₂), silicon nitride(Si₃N₄), TiO₂, Ta₂O₅, or a combination thereof; the examples of themetal material include gold, aluminum, copper, or nickel.

As shown in FIG. 1A and FIG. 1B, the electric contact layer 120 has amaximum of a second width W2 and is disposed on the base layer 110. Morespecifically, the electric contact layer 120 may have a trapezoidalprofile in a cross-sectional view in practical implementation. It isnoted that the maximum of the second width W2 is smaller than or equalto the maximum of the first width W1. The semiconductor stack 130 has amaximum of a third width W3 and is disposed on the electric contactlayer 120. The semiconductor stack 130 may have a trapezoidal profile ina cross-sectional view in practical implementation. More specifically,the semiconductor stack 130 includes a first type semiconductor layer132, a light emitting layer 134, and a second type semiconductor layer136 stacked in sequence on the electric contact layer 120. The firsttype semiconductor layer 132, the light emitting layer 134, and thesecond type semiconductor layer 136 may have respective trapezoidalprofiles in a cross-sectional view in practical implementation. It canbe understand that a width of the first type semiconductor layer 132, awidth of the light emitting layer 134, and a width of the second typesemiconductor layer 136 may be substantially smaller than or equal tothe maximum of the third width W3. It is noted that the maximum of thesecond width W2 is greater than the maximum of the third width W3.

In various embodiments, the first type semiconductor layer 132 may be aP-type III-V group semiconductor layer. For example, the III-V groupsemiconductor layer may include a binary epitaxial material such asGaAs, GaN, GaP, InAs, AlN, InN, and InP, or a ternary or quaternaryepitaxial material such as GaAsP, AlGaAs, InGaP, InGaN, AlInGaP, andInGaAsP. Therefore, the P-type III-V group semiconductor layer may beformed by doping a IIA group element (such as beryllium, magnesium,calcium, or strontium) into the III-V group semiconductor layermentioned above.

In various embodiments, the light emitting layer 134 may include amultiple quantum well (MQW), a single-quantum well (SQW), ahomojunction, a heterojunction, or other similar structures.

In various embodiments, the second type semiconductor layer 136 may bean N-type III-V group semiconductor layer. For example, the III-V groupsemiconductor layer may include a binary epitaxial material such asGaAs, GaN, GaP, InAs, AlN, InN, and InP, or a ternary or quaternaryepitaxial material such as GaAsP, AlGaAs, InGaP, InGaN, AlInGaP, andInGaAsP. Therefore, the N-type III-V group semiconductor layer may beformed by doping a IVA group element (such as silicon) into the III-Vgroup semiconductor layer mentioned above.

In the present embodiment, the electric contact layer 120 includes anohmic contact layer 124 and a first metal layer 122 as shown in FIG. 1Aand FIG. 1B. The ohmic contact layer 124 has a maximum of a fourth widthW4 and is disposed between the semiconductor stack 130 and the baselayer 110. The first metal layer 122 has a maximum of a fifth width W5and is disposed between the ohmic contact layer 124 and the base layer110. More specifically, the ohmic contact layer 124 and the first metallayer 122 may have respective trapezoidal profiles in a cross-sectionalview in practical implementation. It is noted that the maximum of thefourth width W4 is smaller than or substantially equal to the maximum ofthe first width W1 and the maximum of the fifth width W5 issubstantially equal to the maximum of the first width W1. In someembodiments, the ohmic contact layer 124 may include alight-transmitting conductive material or an opaque conductive material.For example, the light-transmitting conductive material may includeindium tin oxide (ITO), IZO, AZO, or other materials withlight-transmitting and conductive properties; and the opaque conductivematerial may include Ni, Ag, Ni/Au alloy or a combination thereof. Insome embodiments, the first metal layer 122 includes Ti, Ni, Al, Au, Pt,Cr, Ag, Cu, or an alloy thereof. It is noted that when the ohmic contactlayer 124 includes light-transmitting conductive material, the firstmetal layer 122 may reflect the light passing through the ohmic contactlayer 124 back so that the light is directed upward, thereby increasingthe light extraction efficiency.

In some embodiments, the electric contact layer 120 is a single layer.In particular, the single-layered electric contact layer 120 may includelight-transmitting conductive material or opaque conductive material.For example, the light-transmitting conductive material may includeindium tin oxide (ITO), IZO, AZO, or other materials withlight-transmitting and conductive properties; and the opaque conductivematerial may include Ni, Ag, Ni/Au alloy or a combination thereof. Inaddition, no matter the electric contact layer 120 is a multi-layered ormono-layered structure, the electric contact layer 120 has a goodelectrical conductivity. Therefore, the interface resistance between theelectric contact layer 120 and the first type semiconductor layer 132may be reduced, thereby decreasing the driving voltage of the lightemitting diode structure 10 and reducing the manufacturing difficultiesof the electric contact layer 120 in the process.

Referring to FIG. 1A and FIG. 1B, the insulation layer 140 at leastcovers a sidewall of the base layer 110, a sidewall of the electriccontact layer 120, and a sidewall of the semiconductor stack 130. Invarious embodiments, the materials of the insulation layer 140 mayinclude silicon oxide, silicon nitride, silicon oxynitride, epoxyresins, or other suitable insulating materials.

In one embodiment, the light emitting diode structure 10 may furtherinclude an electrode layer 150 disposed on the semiconductor stack 130,and a portion of the electrode layer 150 is exposed outside theinsulation layer 140, as shown in FIG. 1A and FIG. 1B. In oneembodiment, the insulation layer 140 covers at least a sidewall of theelectrode layer 150. In some embodiments, the insulation layer 140 maycover both the sidewall of the electrode layer 150 and a portion of atop surface of the electrode layer 150. In addition, in otherembodiments, the insulation layer 140 covers only a portion of the uppersurface of the semiconductor stack 130, thereby forming an opening. Theremaining upper surface of the semiconductor stack 130 is exposed fromthe opening of the insulation layer 140. The electrode layer 150 may bedisposed in the opening of the insulation layer 140 and contacts thesemiconductor stack 130. Alternatively, the electrode layer 150 mayfurther cover a portion of the top surface of the insulation layer 140.The portion of the electrode layer 150 exposed outside the insulationlayer 140 acts as a stage for electrical contact.

In one embodiment, the electrode layer 150 is transparent for the lightemitted by the light emitting layer 134. It is understood that theelectrode layer 150 includes light-transmitting conductive material. Forexample, the light-transmitting conductive material may include indiumtin oxide (ITO), IZO, AZO, or other materials with light-transmittingand conductive properties. In addition, since the light-transmittingconductive material mentioned above has a good electrical conductivity,the surface resistance of the second type semiconductor layer 136 may bereduced, thereby decreasing the driving voltage of the light emittingdiode structure 10 and reducing the manufacturing difficulty of theelectrode layer 150 in the process. In the embodiment where theelectrode layer 150 includes light-transmitting conductive materials,the width of the electrode layer 150 is typically equal to the maximumof the third width W3 of the semiconductor stack 130 to make themanufacturing process become easier.

In another embodiment, the electrode layer 150 may also include opaquemetal materials. For example, the electrode layer 150 is a second metallayer. For example, the opaque metal material may include Cr, GeAu, Au,Ti, Al, or other similar opaque metal materials. In the embodiment wherethe electrode layer 150 includes opaque metal material, in order not toaffect the light emitting efficiency of the light emitting diode, thewidth of the electrode layer 150 is typically smaller than the maximumof the third width W3 of the semiconductor stack 130. For example, thewidth of the electrode layer 150 is as small as possible so long as itis sufficient to provide a contact area for the external wires.

In one embodiment, the light emitting diode structure 10 furtherincludes a bonding substrate 170 as shown in FIG. 1A and FIG. 1B. Inparticular, the base layer 110, the electric contact layer 120, thesemiconductor stack 130, and the insulation layer 140 are disposed onthe bonding substrate 170. In some embodiments of the present invention,the bonding substrate 170 may be a rigid printed circuit board, analuminum substrate with a high thermal conductivity coefficient, aceramic substrate, a flexible printed circuit board, a metal-compositeboard, a light emitting substrate, or a semiconductor substrate withfunctional elements such as transistors and integrated circuits (ICs).In one embodiment, the light emitting diode structure 10 may furtherinclude an adhesive layer 160 disposed between the bonding substrate 170and the base layer 110 to improve the bonding strength there between. Insome embodiments of the present invention, the adhesive layer 160 mayinclude insulating glue, conductive glue and/or suitable metals. Forexample, the material of the adhesive layer 160 may be an insulatingglue such as epoxy resin or silicone; alternatively the material of theadhesive layer 160 may be a conductive glue such as an epoxy resin mixedwith silver powders. Furthermore, the material of the adhesive layer 160may be a metallic material such as copper, aluminum, tin, gold, indiumand/or silver, but not limited thereto.

The various embodiments of FIG. 1A and FIG. 1B will be describedhereinafter, and the following description merely describes thedifferences between these embodiments, and the repeated portions willnot be described again. Referring to FIG. 1A, the electric contact layer120 of the light emitting diode structure 10 includes the ohmic contactlayer 124 and the first metal layer 122, and the first metal layer 122is disposed between the ohmic contact layer 124 and the base layer 110in this embodiment. The first type semiconductor layer 132 and thesecond type semiconductor layer 136 in the semiconductor stack 130 arerespectively a P-type and an N-type III-V group semiconductor layer(such as including GaN). The electrode layer 150 disposed on thesemiconductor stack 130 includes a light-transmitting conductivematerial (such as ITO). In this embodiment, the maximum of the firstwidth W1 of the base layer 110 is substantially equal to the maximum ofthe second width W2 of the electric contact layer 120, wherein themaximum of the fourth width W4 of the ohmic contact layer 124 issubstantially equal to the maximum of the fifth width W5 of the firstmetal layer 122, and the maximum of the second width W2 of the electriccontact layer 120 is greater than the maximum of the third width W3 ofthe semiconductor stack 130.

Referring to FIG. 1B, the difference between the light emitting diodestructure 10 illustrated in FIG. 1B and the light emitting diodestructure 10 illustrated in FIG. 1A is that: the maximum of the firstwidth W1 of the base layer 110 is substantially equal to the maximum ofthe fifth width W5 of the first metal layer 122, the maximum of thethird width W3 of the semiconductor stack 130 is substantially equal tothe maximum of the fourth width W4 of the ohmic contact layer 124, andthe maximum of the fifth width W5 of the first metal layer 122 isgreater than the maximum of the third width W3 of the semiconductorstack 130.

FIG. 2 is cross-sectional view schematically illustrating a lightemitting diode structure, in accordance with another embodiment of thepresent invention. To make it easy to compare the differences betweenthe embodiments in FIGS. 1A-1B and the embodiments in FIG. 2, and inorder to simplify the descriptions, the same symbols are used to labelthe same members in the following various embodiments and mainly thedifferences between the various embodiments are described whilerepetitive parts are not described again.

The difference between the light emitting diode structure 20 illustratedin FIG. 2 and the light emitting diode structure 10 illustrated in FIG.1A is that: the base layer 110 of the light emitting diode structure 20includes a distributed bragg reflector (DBR). The electric contact layer120 is a single layer including light-transmitting conductive material.For example, the light-transmitting conductive material may includeindium tin oxide (ITO), IZO, AZO, or other materials withlight-transmitting and conductive properties. Since thelight-transmitting conductive materials mentioned above has a goodelectrical conductivity, the surface resistance of the first typesemiconductor layer 132 may be reduced, thereby decreasing the drivingvoltage of the light emitting diode structure 20 and reducing themanufacturing difficulty of the electric contact layer 120 in theprocess. The electric contact layer 120 has a maximum of a second widthW2. In particular, the distributed bragg reflector may be comprised oftwo kinds of thin films (homogeneous or heterogeneous) with differentrefractive indices alternatively stacked with each other. Thedistributed bragg reflector may reflect the light emitted from the lightemitting layer 134 in the semiconductor stack 130 and directs the lightin a direction away from the bonding substrate 170 to improve theluminous efficiency of the light emitting diode structure 20. It isnoted that the maximum of the second width W2 is greater than themaximum of the third width W3.

FIG. 3 is cross-sectional view schematically a light emitting diodestructure, in accordance with yet another embodiment of the presentinvention. To make it easy to compare the differences between variousembodiments and in order to simplify the descriptions, the same symbolsare used to label the same members in the following various embodimentsand mainly the differences between the various embodiments are describedwhile repetitive parts are not described again.

As shown in FIG. 3, the light emitting diode structure 30 includes asemiconductor stack 130, an insulation layer 140, a first conductive pad192, a second conductive pad 194, and a supporting breakpoint SP. Inparticular, the semiconductor stack 130 includes a first typesemiconductor layer 132, a light emitting layer 134, and a second typesemiconductor layer 136 stacked in sequence from top to bottom. Thesecond type semiconductor layer 136 includes a first portion 136 a and asecond portion 136 b, and the first portion 136 a is disposed on thesecond portion 136 b. In one embodiment, a width of the first typesemiconductor layer 132, a width of the light emitting layer 134, and awidth of the first portion 136 a of the second type semiconductor layer136 may be the same. It noted that a width of the second portion 136 bof the second type semiconductor layer 136 is greater than the width ofthe first portion 136 a. In other words, the second type semiconductorlayer 136 has a trapezoidal profile in a cross-sectional view. Theinsulation layer 140 covers a sidewall of the semiconductor stack 130and an upper surface of the second portion 136 b. It is noted that theinsulation layer 140 has a first opening 140 a and a second opening 140b respectively positioned on the first type semiconductor layer 132 andthe second portion 136 b of the second type semiconductor layer 136. Thefirst conductive pad 192 is connected to the first type semiconductorlayer 132 through the first opening 140 a, and the second conductive pad194 is connected to the second portion 136 b of the second typesemiconductor layer 136 through the second opening 140 b. In someembodiments, the first conductive pad 192 extends to cover a portion ofa top surface 140 t of the insulation layer 140. In one embodiment, atop surface 192 t of the first conductive pad 192 is substantially levelwith a top surface 194 t of the second conductive pad 194. Thesupporting breakpoint SP is positioned on the insulation layer 140 andbetween the first conductive pad 192 and the second conductive pad 194.

Referring to FIG. 3, in one embodiment, the light emitting diodestructure 30 further includes an electrode layer 150 disposed betweenthe first type semiconductor layer 132 and the first conductive pad 192.In one embodiment, the light emitting diode structure 30 furtherincludes a bonding substrate 170. The first conductive pad 192 and thesecond conductive pad 194 of the light emitting diode structure 30 areelectrically connected to the bonding substrate 170. Namely, the firstconductive pad 192 and the second conductive pad 194 of the lightemitting diode structure 30 are electrically connected to the bondingsubstrate 170 in a manner of “flip-chip”. In some embodiments, the lightemitting diode structure 30 may further include a first adhesive layer162 and a second adhesive layer 164. More specifically, the firstadhesive layer 162 is disposed between the first conductive pad 192 andthe bonding substrate 170, and the second adhesive layer 164 is disposedbetween the second conductive pad 194 and the bonding substrate 170. Itis noted that the first adhesive layer 162 is electrically insulatedfrom the second adhesive layer 164 to avoid a short circuit between thefirst conductive pad 192 and the second conductive pad 194. In variousexamples, the first adhesive layer 162 and the second adhesive layer 164are transparent conductive adhesive layers. For example, the transparentconductive adhesive layer includes epoxy resins mixed with silverpowders or anisotropic conductive films (ACFs).

Referring to FIG. 3, in some embodiments, the light emitting diodestructure 30 further includes a conductive block 180. The conductiveblock 180 is disposed in the second opening 140 b, and the secondconductive pad 194 covers a top surface 180 t and a sidewall 180 s ofthe conductive block 180. In one embodiment, a top surface 140 t of theinsulation layer 140 over the electrode layer 150 is substantially levelwith the top surface 180 t of the conductive block 180.

Another aspect of the present invention is to provide a method formanufacturing a light emitting diode structure 10. FIG. 4 to FIG. 16Bare cross-sectional views illustrating various process stages ofmanufacturing the light emitting diode structure 10, in accordance withone embodiment of the present invention.

As shown in FIG. 4, a precursor structure 40 is provided. The precursorstructure 40 includes an electrode layer 370, a semiconductor stack320′, an ohmic contact layer 330, a metal layer 332, a base layer 340 a,and a sacrificial layer 350 stacked in sequence on a carrier substrate360 from top to bottom.

FIG. 5 to FIG. 9 are cross-sectional views illustrating various processstages of manufacturing the precursor structure mention above, inaccordance with one embodiment of the present invention. Referring toFIG. 5, an epitaxial stack 320 is formed on a growth substrate 310. Inone embodiment, the epitaxial stack 320 may be formed on the growthsubstrate 310 by epitaxial growth techniques. In one embodiment, thegrowth substrate 310 may be a sapphire substrate or other suitablesubstrates. In various embodiments, the epitaxial stack 320 includes anundoped semiconductor layer 328, a second type semiconductor layer 326,a light emitting layer 324, and a first type semiconductor layer 322stacked on the growth substrate 310 in sequence. In some embodiments,the undoped semiconductor layer 328 is an undoped III-V groupsemiconductor layer. For example, the undoped III-V group semiconductorlayer may include binary an epitaxial material such as GaAs, GaN, GaP,InAs, AlN, InN, and InP, or ternary or quaternary epitaxial materialssuch as GaAsP, AlGaAs, InGaP, InGaN, AlInGaP, and InGaAsP. In someembodiments, the second type semiconductor layer 326 is an N-type III-Vgroup semiconductor layer and the first type semiconductor layer 322 isa P-type III-V group semiconductor layer. It should be understood thatthe N-type III-V group semiconductor layer may be formed by doping anIVA group element (such as silicon) into the undoped III-V groupsemiconductor layer mentioned above and the P-type III-V groupsemiconductor layer may be formed by doping an IIA group element (suchas beryllium, magnesium, calcium, or strontium) into the undoped III-Vgroup semiconductor layer mentioned above. In various embodiments, thelight emitting layer 324 may include a multiple quantum well (MQW), asingle-quantum well (SQW), a homojunction, a heterojunction, or othersimilar structures.

Referring to FIG. 5, an ohmic contact layer 330, a metal layer 332, anda base layer 340 a are formed and stacked on the epitaxial stack 320 insequence from bottom to top. In the present embodiment, the ohmiccontact layer 330 may include light-transmitting conductive materials oropaque conductive materials. For example, the light-transmittingconductive material may include indium tin oxide (ITO), IZO, AZO, ormaterials with light-transmitting and conductive properties; and theopaque conductive material may include Ni, Ag, Ni/Au alloy, or acombination thereof. The material of the metal layer 332 may be the sameas the first metal layer 122 described hererinbefore, and will not bedescribed hereinafter. In the present embodiment, the base layer 340 amay include a dielectric material or a metal material. For example, thedielectric material may include silicon dioxide (SiO₂), silicon nitride(Si₃N₄), TiO₂, Ta₂O₅, or a combination thereof; and the metal materialmay include gold, aluminum, copper, or nickel.

Referring to FIG. 6, a sacrificial layer 350 is formed on the base layer340 a. In various embodiments, the sacrificial layer 350 includesbenzocyclobutene (BCB) or polyimide (PI).

Referring to FIG. 7, a carrier substrate 360 is then formed on thesacrificial layer 350. In various embodiments, the carrier substrate 360may be a silicon substrate or other suitable substrates. It should bestated that after forming the sacrificial layer 350 on the carriersubstrate 360, the structure as shown in FIG. 7 is flipped upside downso that the growth substrate 310 is at the top and the carrier substrate360 is at the bottom.

Referring to FIG. 8, the growth substrate 310 is removed. In someembodiments, the growth substrate 310 may be removed by laser lift-off(LLO), grinding, or etching. In particular, the growth substrate 310 isremoved to expose the undoped semiconductor layer 328 of the epitaxialstack 320.

Referring to FIG. 9, subsequently, a portion of the epitaxial stack 320is removed to form a semiconductor stack 320′. More specifically, theundoped semiconductor layer 328 of the epitaxial stack 320 does not havea conductive function, so the undoped semiconductor layer 328 of theepitaxial stack 320 is completely removed in this step and the secondtype semiconductor layer 326 is exposed. After this step, thesemiconductor stack 320′ (that is the remaining epitaxial stack)includes the second type semiconductor layer 326, the light emittinglayer 324, and the first type semiconductor layer 322 stacked on theohmic contact layer 330 from top to bottom in sequence.

Then, the electrode layer 370 is formed on the semiconductor stack 320′to complete the precursor structure 40 as shown in FIG. 4. In oneembodiment, the electrode layer 370 includes light-transmittingconductive materials. For example, the light-transmitting conductivematerial may include indium tin oxide (ITO), IZO, AZO, or materials withlight-transmitting and conductive properties. In addition, since thelight-transmitting conductive materials mentioned above has a goodelectrical conductivity, the surface resistance of the second typesemiconductor layer 326 may be reduced, thereby decreasing the drivingvoltage of the light emitting diode and reducing the difficulty in theprocess of manufacturing the electrode layer 370. In another embodiment,the electrode layer 370 may also include opaque metal materials. Forexample, the opaque metal material may include Cr, GeAu, Au, Ti, Al, orother similar opaque metal materials.

Next, a portion of the electrode layer 370, a portion of thesemiconductor stack 320′, a portion of the ohmic contact layer 330, aportion of the metal layer 332, and a portion of the base layer 340 a inthe precursor structure 40 are removed to expose the sacrificial layer350. FIG. 10A to FIG. 11B are cross-sectional views illustrating thisstep according to one embodiment of the present invention. There are tworemoval processes included in this step. As shown in FIG. 10A, in oneembodiment, the first removal process may utilize a lithography processto remove the portion of the electrode layer 370 and the portion of thesemiconductor stack 320′ so to expose the ohmic contact layer 330. Inthis embodiment, the remaining semiconductor stack 320″ and theremaining electrode layer 370′ have the same width. As shown in FIG.10B, in another embodiment, the first removal process may utilize alithography process to remove a portion of the electrode layer 370, aportion of the semiconductor stack 320′, and a portion of the ohmiccontact layer 330 so to expose the metal layer 332. In the embodiment,the remaining semiconductor stack 320″, the remaining electrode layer370′, and the remaining ohmic contact layer 330′ have the same width. Itshould be noted that, in the embodiment where the electrode layer 370includes light-transmitting conductive materials, the width of theremaining semiconductor stack 320″ after etching is substantially equalto the width of the remaining electrode layer 370′. In the embodimentwhere the electrode layer 370 includes opaque metal materials, in ordernot to affect the light extraction efficiency of the light emittingdiode, the width of the remaining electrode layer 370′ after etching isusually smaller than the width of the remaining semiconductor stack320″. For example, the width of the remaining electrode layer 370′ is assmall as possible so long as it is sufficient to provide a contact areafor the external wires.

As shown in FIG. 11A, in one embodiment, the second removal process mayutilize a lithography process to remove a portion of the ohmic contactlayer 330, a portion of the metal layer 332, and a portion of the baselayer 340 a so to expose the sacrificial layer 350. In this embodiment,the remaining ohmic contact layer 330′, the remaining metal layer 332′,and the remaining base layer 340 a′ have substantially the same width,and the width of the remaining ohmic contact layer 330′ is greater thanthe width of the remaining semiconductor stack 320″. As shown in FIG.11B, in another embodiment, the second removal process may utilize alithography process to remove a portion of the metal layer 332 and aportion of the base layer 340 a so to expose the sacrificial layer 350.In this embodiment, the remaining metal layer 332′ and the remainingbase layer 340 a′ substantially have the same width, and the width ofthe remaining metal layer 332′ is greater than the width of theremaining semiconductor stack 320″.

FIG. 12 illustrates a top view in one process stage of manufacturing thelight emitting diode structure. FIG. 13 to FIG. 15 are cross-sectionalviews along line A-A′ in FIG. 12, that illustrate various process stagesin accordance with some embodiments. FIG. 16A to FIG. 16B arecross-sectional views along line B-B′ in FIG. 12 illustrating one ofprocess stages of manufacturing the light emitting diode structure. Itshould be noted that in FIG. 13 to FIG. 15, due to the position of thecutting line A-A′, the remaining base layer 340 a′, the remaining metallayer 332′, the remaining ohmic contact layer 330′, the remainingsemiconductor stack 320″, and the remaining electrode layer 370′ havethe same width.

Referring to FIG. 13 and FIG. 14, an opening 352 is formed in thesacrificial layer 350 to expose a portion of the carrier substrate 360.Specifically, the opening 352 is adjacent to the remaining multilayeredstructure (including 340 a′, 332′, 330′, 320″, and 370′) after theetching process. It should be noted that the opening 352 is not a partof the light emitting diode structure.

Next, referring to FIG. 14, an insulation layer 380 is formed tocontinuously cover the remaining base layer 340 a′, the remaining metallayer 332′, the remaining ohmic contact layer 330′, the remainingsemiconductor stack 320″, the remaining electrode layer 370′, a portion350 a of a top surface of the sacrificial layer 350, the opening 352,and the exposed portion of the carrier substrate 360. In particular, theinsulation layer 380 has a first portion 380 a covering the portion 350a of the top surface of the sacrificial layer 350, and the insulationlayer 380 has a second portion 380 b coupling to the first portion 380 aand covering a sidewall of the remaining multilayered structure(including 340 a′, 332′, 330′, 320″, and 370′). The first portion 380 aand the second portion 380 b of the insulation layer 380 constitute an“L” type. A portion of the sacrificial layer 350 uncovered by theinsulation layer 380 (that is the exposed portion 350P) and the portion350 a, which is covered by the first portion 380 a of the insulationlayer 380, of the top surface of the sacrificial layer 350 are locatedon opposite sides of the remaining multilayer structure (including 340a′, 332′, 330′, 320″, and 370′). In some embodiments of the presentinvention, the materials of the insulation layer 380 are the same asthese described hereinbefore in connection with the insulation layer140, and will not be described herein. In some embodiments of thepresent invention, the insulation layer 380 may be formed by usingchemical vapor deposition, printing, coating, or other suitable methods.In particular, the insulation layer 380 has a thickness ranged fromabout 500 Å to about 20000 Å. According to various embodiments, when thethickness of the insulation layer 380 is greater than a certain valuesuch as 20000 Å, it will lead to an increase in the manufacturing cost.To the contrary, when the thickness of the insulation layer 380 is lessthan a certain value such as 500 Å, it will cause the lack of supportforce in the following processes. Therefore, the thickness of theinsulation layer 380 may be such as 600 Å, 700 Å, 800 Å, 900 Å, 1000 Å,2000 Å, 3000 Å, 4000 Å, 5000 Å, 6000 Å, 7000 Å, 8000 Å, 9000 Å, 10000 Å,or 15000 Å.

Referring to FIG. 15, FIG. 16A, and FIG. 16B, the sacrificial layer 350is removed. More specifically, the sacrificial layer 350 may be removedfrom the exposed portion 350P of the sacrificial layer by using anetching solution. As shown in FIG. 15, after the sacrificial layer 350is etched, a portion of the insulation layer 380 may constitute asupporter 382. The remaining electrode layer 370′, the remainingsemiconductor stack 320″, the remaining ohmic contact layer 330′, theremaining metal layer 332′, and the remaining base layer 340 a′ aresuspended over the carrier substrate 360 by the supporter 382. Sinceonly the supporter 382 is left to support the upper structure afterremoving the sacrificial layer 350, it is easy to break the supporter382. In addition, only a portion of the sacrificial layer 350 isnecessary to be removed in some embodiments. For example, merely aportion of the sacrificial layer 350 is removed from the upper surfaceof the sacrificial layer 350 such that the remaining electrode layer370′, the remaining semiconductor stack 320″, the remaining ohmiccontact layer 330′, the remaining metal layer 332′, and the remainingbase layer 340 a′ are suspended over the carrier substrate 360. That isto say, it is not necessary to completely remove the sacrificial layer350 as long as the supporter 382 can be broken. In FIG. 16A and FIG.16B, the insulation layer 380 covers at least a sidewall of theremaining base layer 340 a′, a sidewall of the remaining metal layer332′, a sidewall of the remaining ohmic contact layer 330′, a sidewallof the remaining semiconductor stack 320″, and a sidewall of theremaining electrode layer 370′. Further, a portion 330′a of the topsurface of the remaining ohmic contact layer 330′ or a portion 332′a ofthe top surface of the remaining metal layer 332′ is exposed. In someembodiments, the insulation layer 380 may also cover a portion of thetop surface of the remaining electrode layer 370′.

Please referring back to FIG. 15, the supporter 382 of the insulationlayer 380 is then intentionally to be broken, thereby forming anindividual light emitting diode structure. It should be noted that afterthe operation of breaking the supporter 382, a supporting breakpoint SPwould be formed in each individual light emitting diode structure. Morespecifically, the supporting breakpoint SP may include the supporter 382broken at a transition position 382P of the first portion 380 a and thesecond portion 380 b, the supporter 382 broken at any position of thefirst portion 380 a, or a sidewall on which a portion of the secondportion 380 b is detached from the remaining multilayer structure (340a′, 332′, 330′, 320″, or 370′). In some embodiments, the individuallight emitting diode structure may be disposed on the bonding substrate170 so to form the light emitting diode structure 10 as shown in FIG. 1Aand FIG. 1B. In addition, the adhesive layer 160 may be formed on thebonding substrate 170 first, and then the individual light emittingdiode structure may be disposed on the adhesive layer 160 to enhance theadhesion there between. The various features of the micro light emittingdiode structure 10 as shown in FIG. 1A and FIG. 1B have been describedhereinbefore, and the details are not repeated herein. It is noted thatthe processes or operations described above are illustrated for examplesonly, and each operation can be arbitrarily changed according to therequirements. In some embodiments, additional operations can beperformed before, during or after the process above.

Another embodiment of the present invention is to provide a method formanufacturing a light emitting diode structure 10. FIG. 17 to FIG. 25are cross-sectional views illustrating various process stages ofmanufacturing the light emitting diode structure 10, in accordance withsome embodiments of the present invention. As shown in FIG. 17, aprecursor structure is provided first. The precursor structure 50includes an electrode layer 370, a semiconductor stack 320′, an ohmiccontact layer 330, a base layer 340 a, a sacrificial layer 350, asupporting layer 410, and a carrier substrate 360 stacked from top tobottom in sequence. In one embodiment, the precursor structure 50 mayfurther include a metal layer 332 disposed between the ohmic contactlayer 330 and the base layer 340 a. In another embodiment, the precursorstructure 50 may further include an adhesive layer 420 disposed betweenthe supporting layer 410 and the carrier substrate 360. The descriptionbelow is made to describe the embodiments of the precursor structure 50including the metal layer 332 and the adhesive layer 420.

FIG. 18 to FIG. 22 are cross-sectional views illustrating variousprocess stages of manufacturing the precursor structure mention above,in accordance with one embodiment of the present invention. Referring toFIG. 18, an epitaxial stack 320, an ohmic contact layer 330, a metallayer 332, a base layer 340 a, and a sacrificial layer 350 are formed insequence on the growth substrate 310 from bottom to top. In particular,the epitaxial stack 320 includes an undoped semiconductor layer 328, asecond type semiconductor layer 326, a light emitting layer 324, and afirst type semiconductor layer 322 are stacked on the growth substrate310 in sequence. It should be noted that the sacrificial layer 350 hasan opening 350R exposing a portion of the base layer 340 a.

Next, a supporting layer 410 is formed and covers the sacrificial layer350 and fills the opening 350R as shown in FIG. 19. In some embodiments,the supporting layer 410 may include insulating materials, metallicmaterials, or other supporting materials. For example, the insulatingmaterials include silicon dioxide, silicon nitride, silicon oxynitride,and epoxy resin; and the metallic materials include aluminum, titanium,gold, platinum, or nickel, but not limited thereto.

Referring to FIG. 20, the carrier substrate 360 is subsequently formedon the supporting layer 410. In some embodiments, the carrier substrate360 can be adhered to the supporting layer 410 by an adhesive layer 420to enhance the adhesion between the carrier substrate 360 and thesupporting layer 410. In one embodiment, the materials of the adhesivelayer 420 may include insulation glue, conductive glue and/or metals.For example, the materials of the adhesive layer 420 may be insulationglue such as an epoxy resin or a silicone; the materials of the adhesivelayer 420 may be conductive glue such as an epoxy resin mixed withsilver powders; the materials of the adhesive layer 420 may be a metalsuch as copper, aluminum, tin, gold, indium and/or silver, but notlimited thereto. It should be stated that after forming the carriersubstrate 360, the structure as shown in FIG. 20 is flipped upside downso that the growth substrate 310 is at the top and the carrier substrate360 is at the bottom.

Referring to FIG. 21, the growth substrate 310 is then removed. In someembodiments, the growth substrate 310 may be removed by laser lift-off(LLO), gridding, or etching processes. In particular, the growthsubstrate 310 is removed to expose the undoped semiconductor layer 328of the epitaxial stack 320.

Referring to FIG. 22, subsequently, a portion of the epitaxial stack 320is removed to form a semiconductor stack 320′. More specifically, theundoped semiconductor layer 328 of the epitaxial stack 320 is notconductive, so the undoped semiconductor layer 328 of the epitaxialstack 320 is completely removed in this step, and the second typesemiconductor layer 326 is exposed. After this step, the semiconductorstack 320′ (i.e., the remaining epitaxial stack) includes the secondtype semiconductor layer 326, the light emitting layer 324, and thefirst type semiconductor layer 322 stacked on the ohmic contact layer330 from top to bottom in sequence. Then, the electrode layer 370 isformed on the semiconductor stack 320′ to complete the precursorstructure 50 as shown in FIG. 17.

Next, a portion of the electrode layer 370, a portion of thesemiconductor stack 320′, a portion of the ohmic contact layer 330, aportion of the metal layer 332, and a portion of the base layer 340 a inthe precursor structure 50 as shown in FIG. 17 are removed to expose thesacrificial layer 350. FIG. 23 to FIG. 24 are cross-sectional viewsillustrating an approach of implementing this step according to oneembodiment of the present invention. There are two removal processesincluded in this step. As shown in FIG. 23, in one embodiment, the firstremoval process may utilize a lithography process to remove a portion ofthe electrode layer 370 and a portion of the semiconductor stack 320′ soto expose the ohmic contact layer 330. In this embodiment, the remainingsemiconductor stack 320″ and the remaining electrode layer 370′ havesubstantially the same width.

In one embodiment, the second removal process may utilize a lithographyprocess to remove the portion of the ohmic contact layer 330, theportion of the metal layer 332, and the portion of the base layer 340 aso that the sacrificial layer 350 is exposed, as shown in FIG. 24. Inthis embodiment, the remaining ohmic contact layer 330′, the remainingmetal layer 332′, and the remaining base layer 340 a′ have substantiallythe same width. The width of the remaining ohmic contact layer 330′ isgreater than the width of the remaining semiconductor stack 320″. Inactual operations, a certain sidewall of the remaining ohmic contactlayer 330′ is not accurately aligned (or flushed) with the sidewall ofthe same side of the remaining semiconductor stack 320″ due to processtolerances in the second removal process.

Referring to FIG. 24, an insulation layer 380 is formed continuously tocover the remaining base layer 340 a′, the remaining metal layer 332′,the remaining ohmic contact layer 330′, the remaining semiconductorstack 320″, and the remaining electrode layer 370′. It should be notedthat the insulation layer 380 does not completely cover the sacrificiallayer 350. That is, a portion of the sacrificial layer 350 is exposed.Thereafter, in one embodiment, a first opening 380R1 and a secondopening 380R2 may be formed in the insulation layer 380 by lithographyetching to expose a portion of the remaining electrode layer 370′ and aportion of the remaining ohmic contact layer 330′, respectively.

Referring to FIG. 25, the sacrificial layer 350 is removed. Morespecifically, the sacrificial layer 350 may be removed from the exposedportion of the sacrificial layer 350 by using an etching solution. Afterthe sacrificial layer 350 is etched, a portion of the supporting layer410 may constitute a supporter 412. The insulation layer 380, theremaining electrode layer 370′, the remaining semiconductor stack 320″,the remaining ohmic contact layer 330′, the remaining metal layer 332′,and the remaining base layer 340 a′ are suspended over the supportinglayer 410 by the supporter 412. Since only the supporter 412 is left tosupport the upper structure after removing the sacrificial layer 350, itis easy to break the supporter 412. In addition, in some embodiments,only a portion of the sacrificial layer 350 is removed. For example, aportion of the sacrificial layer 350 is removed from the upper surfaceof the sacrificial layer 350 such that the insulation layer 380, theremaining electrode layer 370′, the remaining semiconductor stack 320″,the remaining ohmic contact layer 330′, the remaining metal layer 332′,and the remaining base layer 340 a′ are suspended over the sacrificiallayer 350. That is to say, it is not necessary to remove the completesacrificial layer 350 as long as the supporter 412 can be broken. InFIG. 25, the insulation layer 380 covers at least a sidewall of theremaining base layer 340 a′, a sidewall of the remaining metal layer332′, a sidewall of the remaining ohmic contact layer 330′, a sidewallof the remaining semiconductor stack 320″, and a sidewall of theremaining electrode layer 370′, and a portion of the remaining electrodelayer 370′ and a portion of the remaining ohmic contact layer 330′ areexposes. In some embodiments, the insulation layer 380 may cover theother portion of the top surface of the remaining electrode layer 370′.

Referring to FIG. 25, the supporter 412 of the supporting layer 410 isintentionally to be broken, thereby forming an individual light emittingdiode structure. In one embodiment, when the supporter 412 is broken, aresidual portion of the supporter 412 may remain on the individual lightemitting diode structure, and the residual portion of the supporter 412will not be cleaned off. In another embodiment, when the supporter 412is broken, a residual portion of the supporter 412 may not remain on theindividual light emitting diode structure. In some embodiments, theindividual light emitting diode structure may be disposed on the bondingsubstrate 170 to form the light emitting diode structure 10 as shown inFIG. 1A. In addition, the adhesive layer 160 may be disposed between thebonding substrate 170 and the individual light emitting diode structureto enhance the adhesion there between. More specifically, the residualportion of the supporter 412 on the individual light emitting diodestructure would be covered by the adhesive layer 160. Therefore, inappearance, the light emitting diode structure 10 shown in FIG. 1A arestill formed. The various features of the light emitting diode structure10 shown in FIG. 1A have been described hereinbefore, and the detailsare not repeated herein. It is noted that the processes and operationsdescribed above are illustrated for examples only, and each operationcan be arbitrarily changed according to the requirements. In someembodiments, additional operations can be performed before, during orafter the process above.

Yet another aspect of the present invention is to provide a method formanufacturing a micro light emitting diode structure 20. FIG. 26 to FIG.38B are cross-sectional views illustrating various process stages ofmanufacturing the light emitting diode structure 20, in accordance withanother embodiment of the present invention.

As shown in FIG. 26, a precursor structure 60 is provided first. Theprecursor structure 60 includes an electrode layer 370, a semiconductorstack 320′, an ohmic contact layer 330, a base layer 340 b, asacrificial layer 350, and a carrier substrate 360 stacked from top tobottom in sequence. FIG. 27 to FIG. 30 are cross-sectional viewsillustrating various process stages of manufacturing the precursorstructure mention above, in accordance with one embodiment of thepresent invention. To make it easy to compare differences betweenvarious embodiments and simplify the descriptions, the same symbols areused to label the same members in the following various embodiments andmainly the differences between the various embodiments are describedwhile repetitive parts are not described again. Referring to FIG. 27, anepitaxial stack 320 and an ohmic contact layer 330 are sequentiallyformed on the growth substrate 310 from bottom to top.

Next, referring to FIG. 28, the base layer 340 b is formed on the ohmiccontact layer 330. In the present embodiment, the base layer 340 bincludes a distributed bragg reflector (DBR). The embodiments of thedistributed bragg reflector has been described hereinbefore, and thedetails are not repeated herein. It is noted that, in the presentembodiment, when the base layer 340 b includes the distributed braggreflector, the ohmic contact layer 330 must include onlylight-transmitting conductive materials such as for example indium tinoxide (ITO), IZO, AZO, or materials with light-transmitting andconductive properties.

Referring to FIG. 29, the sacrificial layer 350 is formed on the baselayer 340 b. In various embodiments, the sacrificial layer 350 includesbenzocyclobutene (BCB) or polyimide (PI).

Referring to FIG. 30, the carrier substrate 360 is then formed on thesacrificial layer 350. In various embodiments, the carrier substrate 360may be a silicon substrate or other suitable substrates. It should bestated that after forming the sacrificial layer 350 on the carriersubstrate 360, the structure as shown in FIG. 30 is flipped upside downso that the growth substrate 310 is at the top and the carrier substrate360 is at the bottom.

Referring to FIG. 31, the growth substrate 310 is removed. In someembodiments, the growth substrate 310 may be removed by laser lift-off(LLO), grinding, or etching processes. In particular, the growthsubstrate 310 is removed to expose the undoped semiconductor layer 328of the epitaxial stack 320.

Referring to FIG. 32, subsequently, a portion of the epitaxial stack 320is removed to form a semiconductor stack 320′. More specifically, theundoped semiconductor layer 328 of the epitaxial stack 320 is notconductive, so the undoped semiconductor layer 328 of the epitaxialstack 320 is completely removed in this step and the second typesemiconductor layer 326 is exposed. After this step, the semiconductorstack 320′ (that is the remaining epitaxial stack) includes the secondtype semiconductor layer 326, the light emitting layer 324, and thefirst type semiconductor layer 322 stacked on the ohmic contact layer330 from top to bottom in sequence.

Then, the electrode layer 370 is formed on the semiconductor stack 320′to complete the precursor structure 60 as shown in FIG. 26. In oneembodiment, the electrode layer 370 includes light-transmittingconductive materials. For example, the light-transmitting conductivematerial may include indium tin oxide (ITO), IZO, AZO, or materials withlight-transmitting and conductive properties. In addition, since thelight-transmitting conductive materials mentioned above has a goodelectrical conductivity, the surface resistance of the second typesemiconductor layer 326 may be reduced, thereby decreasing the drivingvoltage of the light emitting diode and reducing the difficulty in theprocess of manufacturing the electrode layer 370. In another embodiment,electrode layer 370 may include opaque metal materials. For example, theopaque metal material may include Cr, GeAu, Au, Ti, Al, or the like.

Next, a portion of the electrode layer 370, a portion of thesemiconductor stack 320′, a portion of the ohmic contact layer 330, anda portion of the base layer 340 b in the precursor structure 60 areremoved to expose the sacrificial layer 350. FIG. 33 to FIG. 34 arecross-sectional views illustrating an approach for implementing thisstep according to one embodiment of the present invention. There are tworemoval processes included in this step. As shown in FIG. 33, the firstremoval process may utilize a lithography process to remove a portion ofthe electrode layer 370 and a portion of the semiconductor stack 320′ soto expose the ohmic contact layer 330. In the embodiment where theelectrode layer 370 includes light-transmitting conductive materials,the width of the remaining semiconductor stack 320″ after etching issubstantially equal to the width of the remaining electrode layer 370′.In the embodiment where the electrode layer 370 includes opaque metalmaterials, in order not to affect the light extraction efficiency of thelight emitting diode, the width of the remaining electrode layer 370′after etching is usually smaller than the width of the remainingsemiconductor stack 320″. For example, the width of the remainingelectrode layer 370′ is as small as possible to so long as it issufficient to provide a contact area for the external wires.

Referring to FIG. 34, the second removal process may utilize alithography process to remove a portion of the ohmic contact layer 330and a portion of the base layer 340 b so to expose the sacrificial layer350. To be specific, the width of the remaining ohmic contact layer 330′is substantially equal to the width of the remaining base layer 340 b,and the width of the remaining ohmic contact layer 330′ is greater thanthe width of the remaining semiconductor stack 320″.

FIG. 35 illustrates a top view in one process stage of manufacturing thelight emitting diode structure 20. FIG. 36 to FIG. 38A arecross-sectional views along line A-A′ in FIG. 35, that illustratevarious process stages of manufacturing the light emitting diodestructure 20, in accordance with the some embodiments. FIG. 38B is across-sectional view, along line B-B′ in FIG. 35, illustrating oneprocess stage of manufacturing the light emitting diode structure 20. Itshould be noted that, due to the position of the line A-A′, theremaining base layer 340 b′, the remaining ohmic contact layer 330′, theremaining semiconductor stack 320″, and the remaining electrode layer370′ shown in FIG. 36 to FIG. 38A have the same width .

Referring to FIG. 35 and FIG. 36, an opening 352 is formed in thesacrificial layer 350 to expose a portion of the carrier substrate 360.

Referring to FIG. 37, an insulation layer 380 is formed to continuouslycover the remaining base layer 340 b′, the remaining ohmic contact layer330′, the remaining semiconductor stack 320″, the remaining electrodelayer 370′, a portion 350 a of a top surface of the sacrificial layer350, the opening 352, and the exposed portion of the carrier substrate360. In particular, the insulation layer 380 has a first portion 380 acovering the portion 350 a of the top surface of the sacrificial layer350, and the insulation layer 380 further has a second portion 380 bcoupling to the first portion 380 a and covering a sidewall of theremaining multilayer structure (including 340 b′, 330′, 320″, and 370′).The first portion 380 a and the second portion 380 b of the insulationlayer 380 constitute an “L” type. A portion of the sacrificial layer 350uncovered by the insulation layer 380 (that is the exposed portion 350P)and the portion 350 a, which is covered by the first portion 380 a ofthe insulation layer 380, of the top surface of the sacrificial layer350 are located on opposite sides of the remaining multilayer structure(including 340 b′, 330′, 320″, and 370′).

Referring to FIG. 38A and FIG. 38B, the sacrificial layer 350 isremoved. More specifically, the sacrificial layer 350 may be removedfrom the exposed portion 350P of the sacrificial layer by using anetching solution. As shown in FIG. 38A, after the sacrificial layer 350is etched, a portion of the insulation layer 380 may constitute asupporter 382. The remaining electrode layer 370′, the remainingsemiconductor stack 320″, the remaining ohmic contact layer 330′, andthe remaining base layer 340 b′ are suspended over the carrier substrate360 by the supporter 382. Since only the supporter 382 is left tosupports the upper structure after removing the sacrificial layer 350,it is easy to break the supporter 382. In addition, in some embodiments,only a portion of the sacrificial layer 350 is removed. For example,merely a portion of the sacrificial layer 350 is removed from the uppersurface of the sacrificial layer 350 such that the remaining electrodelayer 370′, the remaining semiconductor stack 320″, the remaining ohmiccontact layer 330′, and the remaining base layer 340 b′ are suspendedover the carrier substrate 360. That is to say, it is not necessary toremove the complete sacrificial layer 350 as long as the supporter 382can be broken. In FIG. 38B, the insulation layer 380 covers at least asidewall of the remaining base layer 340 b′, a sidewall of the remainingohmic contact layer 330′, a sidewall of the remaining semiconductorstack 320″, and a sidewall of the remaining electrode layer 370′, and aportion 330′a of the top surface of the remaining ohmic contact layer330′ is exposed. The portion 330′a of the top surface of the remainingohmic contact layer 330′ is used as a stage for electrical contact. Insome embodiments, the insulation layer 380 may also cover a portion ofthe top surface of the remaining electrode layer 370′.

Please referring back to FIG. 38A, the supporter 382 of the insulationlayer 380 is intentionally to be broken, thereby forming an individuallight emitting diode structure. It should be noted that after theoperation of breaking the supporter 382, a supporting breakpoint SPwould be formed in the individual light emitting diode structure. Morespecifically, the supporting breakpoint SP may include the supporter 382broken at a transition position 382P of the first portion 380 a and thesecond portion 380 b, the supporter 382 broken at any position of thefirst portion 380 a, or a sidewall on which a portion of the secondportion 380 b is detached from the remaining multilayer structure (340b′, 330′, 320″, or 370′). In some embodiments, the individual lightemitting diode structure may be disposed on the bonding substrate 170 toform the light emitting diode structure 20 shown in FIG. 2. In addition,the adhesive layer 160 may be formed on the bonding substrate 170 first,and then the individual light emitting diode structure may be disposedon the adhesive layer 160 to enhance the adhesion there between. Thevarious features of the micro light emitting diode structure 20 shown inFIG. 2 have been described hereinbefore, and the details are notrepeated herein. It is noted that the processes or operations describedabove are illustrated for examples only, and each operation can bearbitrarily changed according to the requirements. In some embodiments,additional operations can be performed before, during or after theprocess above.

Yet another aspect of the present invention is to provide a method formanufacturing a micro light emitting diode structure 30. FIG. 39 to FIG.50 are cross-sectional views illustrating various process stages ofmanufacturing the light emitting diode structure 30, in accordance withyet some embodiment of the present invention. To make it easy to comparedifferences between various embodiments and simplify the descriptions,the same symbols are used to label the same members in the followingvarious embodiments and mainly the differences between the variousembodiments are described while repetitive parts are not describedagain. As shown in FIG. 39, a precursor structure 70 is provided first.The precursor structure 70 includes an electrode layer 370 and anepitaxial stack 320 stacked on a growth substrate 310 from top to bottomin sequence. In particular, the epitaxial stack 320 includes a firsttype semiconductor layer 322, a light emitting layer 324, a second typesemiconductor layer 326, and an undoped III-V group semiconductor layer328 disposed on the growth substrate 310 from top to bottom, wherein thesecond type semiconductor layer 326 includes a first portion 326 a and asecond portion, and the first portion 326 a is disposed on the secondportion 326 b.

Referring to FIG. 40, a portion of the electrode layer 370 and a portionof the epitaxial stack 320 in the precursor structure 70 shown in FIG.39 are removed such that a width of the remaining first portion 326 a′is smaller than a width of the second portion 326 b. More specifically,only a portion of the second type semiconductor layer 326 is removedduring removal of the portion of the epitaxial stack 320 such that thesecond portion 326 b of the second type semiconductor layer 326 isexposed. Therefore, after this removal step is completed, a width of theremaining electrode layer 370′ is substantially equal to a width of theremaining first type semiconductor layer 322′, a width of the remaininglight emitting layer 324′ is substantially equal to a width of theremaining first type semiconductor layer 322′, and a width of theremaining first portion 326 a′ is substantially equal to a width of theremaining first type semiconductor layer 322′. In one embodiment, thisstep can be accomplished using a lithography process and controlling thetime of the etch process.

Referring to FIG. 41, an insulation layer 380 is formed to cover theremaining precursor structure 70′ shown in FIG. 40. In particular, theinsulation layer 380 is continuously covers the exposed surface of thesecond portion 326 b of the second type semiconductor layer 326, thesidewall of the remaining first portion 326 a′ of the second typesemiconductor layer 326, the sidewall of the remaining light emittinglayer 324′, the sidewall of the remaining first type semiconductor layer322′, and the sidewall and surface of the remaining electrode layer370′.

As shown in FIG. 42, a portion of the insulation layer 380 and a portionof the second portion 326 b of the second type semiconductor layer 326are then removed to expose the undoped semiconductor layer 328. In oneembodiment, this step can be accomplished by using a photolithographyprocess. It should be noted that, after this step is completed, a widthof the second portion 326 b′ of the remaining second type semiconductorlayer 326′ must be greater than a width of the remaining first portion326 a′. Such design allows the second portion 326 b′ of the remainingsecond type semiconductor layer 326′ to act as a stage for electricalcontact.

As shown in FIG. 43, in some embodiments, a conductive block 390 may beformed on the second portion 326 b′ of the remaining second typesemiconductor layer 326′. In one embodiment, the method of forming theconductive block 390 includes, for example, the following steps. First,a patterned mask (not shown) is formed on the insulation layer 380, andthe patterned mask has an opening (not shown) at a position where theconductive block 390 is expected to be formed. Thereafter, the opening380R2 is formed to expose a part of the second portion 326 b′ of theremaining second type semiconductor layer 326′. And then, the conductiveblock 390 is formed in the opening 380R2 by sputtering, evaporation,electroplating, or electroless plating. In some embodiments, theconductive block 390 includes aluminum, copper, nickel, gold, platinum,titanium, or other suitable metal materials. In some embodiments, a topsurface 380 t of the insulation layer 380 on the remaining electrodelayer 370′ is substantially leveled with a top surface 390 t of theconductive block 390.

As shown in FIG. 44, an opening 380R1 is formed in the insulation layer380 on the remaining electrode layer 370′ to expose a portion of theremaining electrode layer 370′. In one embodiment, the method of formingthe opening 380R1 includes, for example, the following steps. Apatterned mask (not shown) is formed on the insulation layer 380, andthe patterned mask has an opening (not shown) at a position where theopening 380R1 is expected to be formed. Thereafter, the opening 380R1 isformed to expose a portion of the remaining electrode layer 370′.

Thereafter, as shown in FIG. 45, a first conductive pad 432 is formed inthe opening 380R1 and a second conductive pad 434 is formed covering thetop surface 390 t and sidewall 390 s of the conductive block 390. Invarious embodiments, the first conductive pad 432 and the secondconductive pad 434 may include aluminum, copper, nickel, gold, platinum,titanium, or other suitable conductive materials. In some embodiments,the first conductive pad 432 and the second conductive pad 434 may beformed by sputtering, evaporation, electroplating, or electrolessplating. In one embodiment, the first conductive pad 432 and the secondconductive pad 434 may be manufactured simultaneously or may bemanufactured separately.

Referring to FIG. 46, a sacrificial layer 350 is formed to cover thestructure illustrated in FIG. 45. More specifically, the sacrificiallayer 350 covers the insulation layer 380, the first conductive pad 432and the second conductive pad 434. It is noted that the sacrificiallayer 350 has an opening 350R exposing the insulation layer 380. Morespecifically, the opening 350R is located between the first conductivepad 432 and the second conductive pad 434.

Referring to FIG. 47, a supporting layer 410 is formed to cover thesacrificial layer 350 and to fill the opening 350R. In some embodiments,the supporting layer 410 may include an insulating material, a metallicmaterial, or other materials with supporting effect. For example, theinsulating materials include silicon dioxide, silicon nitride,silicon-oxy-nitride, and epoxy resin; and the metallic materials includealuminum, titanium, gold, platinum, or nickel, but not limited thereto.

As shown in FIG. 48, a carrier substrate 360 is then formed on thesupporting layer 410. In various embodiments, the carrier substrate 360may be adhered to the supporting layer 410 by an adhesive layer 420 toimprove the bonding strength between the carrier substrate 360 and thesupporting layer 410. It should be stated that after forming the carriersubstrate 360 on the supporting layer 410, the structure as shown inFIG. 48 is flipped upside down so that the growth substrate 310 is atthe top and the carrier substrate 360 is at the bottom. Referring toFIG. 49, the growth substrate 310 and the undoped semiconductor layer328 are then removed and a surface 326 s of the remaining second typesemiconductor layer 326′ is exposed. In one embodiment, the exposedsurface 326 s of the remaining second type semiconductor layer 326′ hasa rough texture (not shown). In various examples, the rough texture mayinclude regular patterns or irregular patterns.

Referring to FIG. 50, the sacrificial layer 350 is removed. Morespecifically, the sacrificial layer 350 may be removed by using anetching solution. After the sacrificial layer 350 is etched, a portionof the supporting layer 410 may constitute a supporter 412. The lightemitting diode structure expected to be formed are suspended over thesupporting layer 410 by the supporter 412. Since only the supporter 412supports the upper structure after removing the sacrificial layer 350,the supporter 412 can be easily broken. In addition, in someembodiments, merely a portion of the sacrificial layer 350 is removed.That is to say, it is not necessary to remove the complete sacrificiallayer 350 as long as the supporter 412 can be broken. Next, thesupporter 412 of the supporting layer 410 is intentionally broken,thereby forming an individual light emitting diode structure. In oneembodiment, when the supporter 412 is broken, a residual portion of thesupporter 412 may remain on the individual light emitting diodestructure, and the residual portion of the supporter 412 will not becleaned off. In another embodiment, when the supporter 412 is broken, aresidual portion of the supporter 412 may not remain on the individuallight emitting diode structure. In other embodiments, in order to breakthe supporter 412, a portion of the insulation layer 380 on theindividual light emitting diode structure may be removed. In someembodiments, the first conductive pad 432 and the second conductive pad434 in the individual light emitting diode structure may be electricallyconnected to the bonding substrate 170 by the first adhesive layer 162and the second adhesive layer 164, respectively, to form the lightemitting diode structure 30 as illustrated in FIG. 3. The variousfeatures of the light emitting diode structure 30 as shown in FIG. 3have been described hereinbefore, and the details are not repeatedherein. It is noted that the processes or operations described above areillustrated for examples only, and each operation can be arbitrarilychanged according to the requirements. In some embodiments, additionaloperations can be performed before, during or after the process above.

The light emitting diode structure and the manufacturing method thereofof the present invention can be applied not only to the conventionallight emitting diode and the micro light emitting diode that the size isreduced to a level of micron meters (μm), but also can be widely appliedto display devices and wearable devices.

In sum, the light emitting diode structure provided in the presentinvention may include the distributed bragg reflector or the metal layerto direct the light emitted from the light emitting diode to emitupward, thereby increasing the light extraction efficiency. Since thewidth of the electrical contact layer in the light emitting diodestructure of the present invention is greater than the width of thesemiconductor stack, the electrical contact layer can serve as a stagefor electrical contact. Furthermore, the electrical contact layer of thelight emitting diode structure in the present invention may furtherinclude a double-layered conductive layer (such as the ohmic contactlayer and the metal layer). The conductive layer is designed to ensurethat the light emitting diode structure has a stage for electricalcontact. In addition, the light emitting diode structure provided in thepresent invention can also utilize the second portion of the second typesemiconductor layer, instead of the electrical contact layer, as a stagefor electrical contact, and the surface having the rough texture exposedby the second portion of the second type semiconductor layer can enhancethe light extraction efficiency.

In addition, as comparing to the conventional manufacturing method thatrequires two times of bonding the temporary substrate and two times ofremoving the temporary substrate, the manufacturing method of the lightemitting diode structure provided in the present invention requires onlyone time of bonding the temporary substrate and only one time ofremoving temporary substrate. There are significant improvements inprocess yield, accuracy associated with the alignment and pitch spacingbetween the light emitting diodes. Moreover, in the process oftransferring the light emitting diode structure, the transfer time ofthe micro light emitting diode can be reduced by using the formation ofthe supporter.

Although the present invention has been described in considerable detailwith reference to certain embodiments thereof, other embodiments arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A light emitting diode structure, comprising: abase layer having a maximum of a first width; an electric contact layerhaving a maximum of a second width and disposed on the base layer; asemiconductor stack having a maximum of a third width and disposed onthe electric contact layer, the semiconductor stack comprising a firsttype semiconductor layer, a light emitting layer, and a second typesemiconductor layer stacked in sequence, wherein a width of the firsttype semiconductor layer, a width of the light emitting layer, and awidth of the second type semiconductor layer are substantially smallerthan or equal to the maximum of the third width; and an insulation layerat least covering a sidewall of the base layer, a sidewall of theelectric contact layer, and a sidewall of the semiconductor stack,wherein the maximum of the second width is greater than the maximum ofthe third width and the maximum of the second width is less than orequal to the maximum of the first width.
 2. The light emitting diodestructure of claim 1, wherein the electric contact layer is a singlelayer, and the maximum of the second width is substantially equal to themaximum of the first width.
 3. The light emitting diode structure ofclaim 1, wherein the electric contact layer comprising an ohmic contactlayer and a first metal layer, the ohmic contact layer with a maximum ofa fourth width is disposed between the semiconductor stack and the baselayer, the first metal layer with a maximum of a fifth width is disposedbetween the ohmic contact layer and the base layer, the maximum of thefourth width is smaller than or substantially equal to the maximum ofthe first width, and the maximum of the fifth width is substantiallyequal to the maximum of the first width.
 4. The light emitting diodestructure of claim 3, wherein the maximum of the fourth width issubstantially equal to the maximum of the third width.
 5. The lightemitting diode structure of claim 1, further comprising an electrodelayer disposed on the semiconductor stack.
 6. The light emitting diodestructure of claim 5, wherein the electrode layer is transparent for alight emitted from the light emitting layer.
 7. The light emitting diodestructure of claim 5, wherein the electrode layer is a second metallayer.
 8. The light emitting diode structure of claim 1, wherein thebase layer comprises a dielectric material or a metal material.
 9. Thelight emitting diode structure of claim 1, wherein the base layercomprises a distributed bragg reflector, and the insulation layer coversat least a sidewall of the distributed bragg reflector.
 10. The lightemitting diode structure of claim 9, wherein the electric contact layeris transparent for a light emitted by the light emitting layer.
 11. Alight emitting diode structure, comprising: a semiconductor stackcomprising a first type semiconductor layer, a light emitting layer, anda second type semiconductor layer stacked from top to bottom insequence, wherein the second type semiconductor layer comprises a firstportion and a second portion, the first portion is disposed on thesecond portion, and a maximum width of the second portion is greaterthan a maximum width of the first portion; an insulation layer coveringa sidewall of the semiconductor stack and an upper surface of the secondportion, the insulation layer having a first opening and a secondopening respectively located on the first type semiconductor layer andthe second portion; a first conductive pad electrically connected to thefirst type semiconductor layer through the first opening; a secondconductive pad electrically connected to the second portion through thesecond opening; and a supporting breakpoint disposed over the insulationlayer and between the first conductive pad and the second conductivepad.
 12. The light emitting diode structure of claim 11, furthercomprising a bonding substrate electrically connected to the firstconductive pad and the second conductive pad.
 13. The light emittingdiode structure of claim 12, further comprising a first adhesive layerand a second adhesive layer respectively disposed between the firstconductive pad and the bonding substrate and between the secondconductive pad and the bonding substrate, wherein the first adhesivelayer is electrically insulated from the second adhesive layer.
 14. Thelight emitting diode structure of claim 11, further comprising anelectrode layer disposed between the first type semiconductor layer andthe first conductive pad.
 15. The light emitting diode structure ofclaim 11, further comprising a conductive block disposed in the secondopening, wherein the second conductive pad covers a sidewall and a topsurface of the conductive block.
 16. The light emitting diode structureof claim 15, wherein a top surface of the insulation layer positioned onthe first portion is substantially level with the top surface of theconductive block.
 17. The light emitting diode structure of claim 11,wherein the first conductive pad extends to cover a portion of theinsulation layer.
 18. The light emitting diode structure of claim 11,wherein a top surface of the first conductive pad is substantially levelwith a top surface of the second conductive pad.
 19. The light emittingdiode structure of claim 11, wherein the second type semiconductor layerhas a surface exposed outside and the surface has a rough texture.